The invention relates to a multi-block heat exchanger with a first heat exchanger unit and at least one second heat exchanger unit attached to the first heat exchanger unit. The first heat exchanger unit includes a first heat exchanger block of pipes having at least one first lateral collecting chamber. The second heat exchanger unit includes a second heat exchanger block of pipes having at least one second lateral collecting chamber. In a heat exchanger of this type, the two or more heat exchanger units are integrated into a common constructional unit. The individual heat exchanger units each contain a block of heat exchanger pipes and can have different heat exchanger media flowing through them in order to bring said media into thermal contact, for example, with an air flow guided away over the blocks of pipes on the outside of the pipes. A multi-block heat exchanger of this type is suitable, for example, as a combined oil cooler and condenser/gas cooler in motor vehicles. With the oil-cooler heat exchanger unit, operating oil, for example of a motor vehicle transmission, which is circulating in an oil circuit can be cooled, while in the condenser or gas-cooler heat exchanger unit a high-pressure refrigerant of a motor vehicle air conditioning system can be condensed or cooled.
It is known, for example from laid-open specifications EP 0 367 078 A1 and EP 0 431 917 A1, to integrate two heat exchanger units having a respective block of flat pipes in a common constructional unit by the two blocks of flat pipes together with the associated, lateral collecting pipes being arranged lying one behind the other in the downward direction of the blocks and being connected to each other by a common, heat-conducting corrugated rib structure.
In the case of a multi-block heat exchanger disclosed in laid-open specification DE 33 44 220 A1, there is accommodated in a lateral cutout of a first block of pipes of a first heat exchanger unit, between lateral connecting tanks thereof, a second block of pipes together with lateral connecting tanks of a further heat exchanger unit, the second block of pipes being welded onto an adjacent closing wall of the first block of pipes.
Laid-open specification DE 195 36 116 A1 describes a heat exchanger, in which a block of pipes/ribs together with two lateral collecting pipes is divided into two regions for different heat exchanger media by the two collecting pipes being subdivided at corresponding points by a transverse partition arrangement into two separate collecting chambers in each case which are assigned dedicated connection structures. At the height of this separating region, instead of the flat pipes which are otherwise provided, a separating web is fitted into the block of pipes/ribs.
The technical problem on which the invention is based is the provision of a multi-block heat exchanger of the type mentioned at the beginning, in which, with relatively little outlay, at least one further heat exchanger unit of flexible construction is attached to a first heat exchanger unit in a largely isolated manner thermally.
According to an embodiment of the present invention, the invention solves this problem by the provision of a multi-block heat exchanger having a first heat exchanger unit and at least one second heat exchanger unit attached to the first heat exchanger unit. The first heat exchanger unit includes a first heat exchanger block of pipes having at least one first lateral collecting chamber. The second heat exchanger unit includes a second heat exchanger block of pipes having at least one second lateral collecting chamber. The first and second collecting chambers are formed by a dedicated collecting pipe in each case. The two collecting pipes are fitted one into the other on end sides of the collecting pipes and are connected in a fluid tight manner. An outer cross section of one collecting pipe in the pipe-connecting region essentially corresponds to an inner cross section of the other collecting pipe. A transverse partition is provided to separate the two collecting chambers. Thus, in the case of this heat exchanger, the blocks of pipes of the different heat exchanger units are provided with dedicated collecting pipes in each case, which makes possible, in particular, the use of collecting pipes having cross sections differing in size for the individual blocks of pipes. Every two heat exchanger units are connected to each other at least via a collecting-pipe connection on the end side by the two collecting pipes which are involved being fitted one into the other on their end sides and being connected in a fluid-tight manner. For this purpose, the collecting pipes are designed in this end-side region in such a manner that the outer cross section of the inserted collecting pipe essentially corresponds to the inner cross section of the collecting pipe fitting around it. A transverse partition provided in the pipe-connecting region keeps the collecting chambers belonging to the two collecting pipes separate from each other. This type of integration of two or more heat exchanger units into a common constructional unit has the advantage of enabling different heat exchanger units to be assembled in a flexible manner to form a multi-block heat exchanger, i.e. various different heat exchanger units can optionally be attached to a given, first heat exchanger unit.
According to another embodiment of the present invention, a multi-block heat exchanger is provided. This embodiment is similar to the first embodiment except that the outer collecting pipe in the pipe-connecting region tapers from a larger central-region cross section to a smaller connecting-region cross section. Additionally, the outer collecting pipe is manufactured by a drawing-in, hammering or expansion process or as an extruded part. Thus, the two collecting pipes of two assembled heat exchanger units have cross sections which differ in size in their central region into which the pipes of the associated block of pipes lead in each case. In order to realize the collecting-pipe connection, the collecting pipe having the larger central-region cross section is tapered in the corresponding end-side connecting region to a smaller cross section which is then just sufficient in order to accommodate the collecting pipe having the smaller cross section. The collecting pipe which is tapered on the end side is manufactured with relatively little outlay by a drawing-in, hammering or expansion process or as an extruded part.
According to another embodiment of the present invention, a multi-block heat exchanger is provided. This embodiment is similar to the first embodiment except that in the pipe-connecting region the outer collecting pipe is solder-plated on its inside or the inner collecting pipe is solder-plated on its outside. Thus, in the pipe-connecting region of the two collecting pipes fitted together the outer collecting pipe is solder-plated on its inside and/or the inner collecting pipe is solder-plated on its outside. This measure enables the two collecting pipes to be connected in a soldering procedure in which the leakproof soldering of the heat exchanger pipes to the collecting pipes and the soldering of heat-conducting ribs, if provided, to the heat exchanger pipes preferably take place at the same time.
According to another embodiment of the present invention, a heat exchanger is provided. This embodiment is similar to the first embodiment except that the two blocks of pipes are arranged lying next to each other in a vertical direction of the blocks. Additionally, there are at least two heat-conducting ribs and/or an air gap and/or a thermally insulating block-closing wall between the heat exchanger pipe of the one block of pipes and the heat exchanger pipe of the other block of pipes that are closest together. Thus, the heat exchanger contains at least two blocks of pipes which are arranged lying next to each other in the vertical direction of the blocks. There are at least two heat-conducting ribs and/or an air gap and/or a thermally insulated block-closing wall between those pipes of the respective block of pipes which lie opposite one another and are in each case the last ones on this side, with the result that these two heat exchanger pipes can, if required, be decoupled thermally from each other to the greatest extent.
According to another embodiment of the present invention, a heat exchanger is provided. This embodiment is similar to the first embodiment except the two blocks of pipes are arranged offset in a downward direction of the blocks. Additionally, one of the two collecting pipes includes a U-bend via which it is guided from the plan of its associated block of pipes to the pipe-connecting region in the plane of the other block of pipes. Thus, at least two heat exchanger units having blocks of pipes offset in the downward direction of the blocks, i.e. in the direction perpendicular with respect to the planes of the blocks of pipes, are provided. In order to realize the end-side collecting-pipe connection of the two heat exchanger units, a collecting pipe of the one heat exchanger unit is provided with a U-bend via which it is guided from the plane of its associated block of pipes into the plane of the other block of pipes, which plane is offset with respect thereto and in which the collecting pipe, which is connected to said U-bend, of the other block of pipes lies. Consequently, by means of this measure a plurality of independent heat exchanger blocks of pipes can be decoupled thermally to the greatest possible extent and, in particular, can be arranged offset in the downward direction of the blocks in a common constructional unit without a common heat-conducting rib connection and without any other common connection of the elements of the blocks of pipes. In the case of a block of pipes through which, for example, air flows on the outside of the pipes, the downward direction of the blocks is parallel in this case to the direction of flow of the medium guided past on the outside of the pipes.
According to another embodiment of the present invention, a multi-block heat exchanger is provided. This embodiment is similar to the first embodiment except that the heat exchanger includes at least two further heat exchanger units having a respective block of pipes and lateral collecting pipes. The two further heat exchanger units are attached to the first heat exchanger unit. The further heat exchanger units are arranged lying opposite one another along an inner collecting-chamber side and adjacent in a vertical direction of the blocks of the first heat exchanger unit. Additionally, an associated outer collecting pipe in each case is connected on an end side to a collecting pipe of the first heat exchanger. Thus, the heat exchanger of this embodiment contains at least three heat exchanger units having associated blocks of pipes, there being arranged on the same side of a first heat exchanger unit two further heat exchanger units lying next to each other in the longitudinal direction of the heat exchanger pipes. The overall width of the two further heat exchanger units, which width is determined essentially by the overall length of the heat exchanger pipes, is preferably selected in such a manner that it corresponds approximately to the width of the third heat exchanger unit, resulting altogether in the formation of a constructional unit having dimensions which remain approximately the same over the regions of the different heat exchanger units. This also facilitates the connection of one collecting pipe in each case of the two further heat exchanger units to a collecting pipe of the first heat exchanger unit, since in this case the collecting pipes which are connected to one another lie largely coaxially with one another. In a further refinement of this heat exchanger, the two further heat exchanger units include a joint, inner, two-channel collecting pipe that has two collecting chambers separated by a longitudinal partition. Thus, the two mutually facing collecting chambers of the two further heat exchanger units are integrated in a compact manner into a common collecting pipe having a corresponding longitudinal partition.
According to another embodiment of the present invention, a multiblock heat exchanger is provided. This embodiment is similar to the first embodiment except the block of pipes of the first heat exchanger unit is formed by flat pipes that are fitted with twisted ends into lateral collecting pipes having an inner diameter that is smaller than the width of the flat pipes. Thus, the cross section of the collecting pipe of at least one of the heat exchanger units is selected such that it is smaller than the width of the flat pipes used for constructing the associated block of pipes. Said flat pipes lead on the underside with twisted end regions into the collecting pipe which is kept relatively thin and can then be fitted on the end side into a collecting pipe of larger cross section of an adjacent heat exchanger unit. Heat exchanger units having such thin collecting pipes are suitable particularly for air conditioning systems having high operating pressures, such as CO2 air conditioning systems.